The present invention relates to measuring and testing, and more particularly to methods and apparatus for determining dimensional characteristics of minute hollow spherical shells.
In a number of industrial and research applications for minute hollow spherical shells or microspheres, uniformity of shell dimensional characteristics, specifically outside diameter and wall thickness, are important considerations. Laser interferometric, microradiographic and microscopic techniques heretofore proposed for measurement of diameter and wall thickness are cumbersome and time consuming, require trained personnel, and are generally unsatisfactory for use on a mass production basis.
Accordingly, an object of the present invention is to provide a method and apparatus for rapid accurate characterization of hollow microshells by untrained personnel. A further object of the invention is to provide a method and apparatus of the type described which requires minimum handling of the microspheres and is readily adaptable for automated operation.